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The foramen magnum is located inferiorly under the skull, which puts much of the weight of the head behind the spine. The flat human face helps to maintain balance on the occipital condyles . Because of this, the erect position of the head is possible without the prominent supraorbital ridges and the strong muscular attachments found in, for ...
With the foramen magnum being position anterior in the cranium, the body of bipedal mammals is given a different center of gravity compared to quadrupedal mammals. The anterior foramen magnum shifts the weight of the body more to the mammals' pelvis and femur, present in some primates, like great apes.
The spinal epidural space spans the length of the spinal cord, from the foramen magnum superiorly to the sacral hiatus inferiorly. [6] Epidural space is the smallest at the cervical region, measuring 1 to 2 mm. At L2 to L3, enlarges until 5 to 6 mm. It then enlarges progressively until lower lumbar and sacral region. [7]
The condyles are oval or reniform (kidney-shaped) in shape, and their anterior extremities, directed forward and medialward, are closer together than their posterior, and encroach on the basilar portion of the bone; the posterior extremities extend back to the level of the middle of the foramen magnum.
The skull was an indicator of orthograde posture because of the location and orientation of the foramen magnum. The foramen magnum is the space in the skull that acts as the bridge to the central nervous system from the spinal cord to the brain. For animals with "pronograde posture, the foramen magnum is dorsally oriented, whereas in humans it ...
The lumbar cistern is part of the subarachnoid space.It is the space within the thecal sac which extends from below the end of the spinal cord (the conus medularis), typically at the level of the first to second lumbar vertebrae down to tapering of the dura at the level of the second sacral vertebra.
The occipital sinus commences around the margin of the foramen magnum [2] by several small venous channels (one of which joins the terminal part of the sigmoid sinus). It terminates by draining into the confluence of the sinuses .
The spinal cord is an extension of the brain. The spinal cord and the brain stem are joined at the base of the cranium at the foramen magnum. Most of the functions of the head and neck are directly influenced by the brain and transmitted to the PNS via the cranial nerves and spinal nerves of the cervical portion of the spine.